1. Field of the Invention
The present invention relates to a solar cell module having a specific heat-sensitive circuit cut-off means, a solar cell array comprising a plurality of solar cell module strings having a specific heat-sensitive circuit cut-off means arranged while being electrically connected with each other in parallel, and a sunlight power generation apparatus comprising said solar cell array. The term "solar cell module" in the present invention means a structural body comprising a plurality of solar cells (photovoltaic elements) electrically connected with each other in series while being sealed by means of a sealing material including an organic sealing resin. The term "solar cell module string" means a string comprising a plurality of solar cell modules arranged while being electrically connected with each other in series.
2. Related Background Art
In recent years, there have been proposed various solar cell modules having a configuration capable of being used as a building material such as so-called roof-integral type solar cell modules. These solar cell modules have been widely put to practical use by installion on a roof or the like of a building. Along with this, certain safty issues upon the occurrence of a fire have arisen for the following reason. The solar cell module comprises a plurality of solar cells (photovoltaic elements) electrically serialized while being sealed by means of a sealing material including an organic sealing resin, where the solar cells comprise inorganic materials which are incombustible, but the organic sealing resin is combustible. Thus, the solar cell module unavoidably contains a combustible material therein. In this connection, for instance, in the case where a plurality of solar cell modules are installed on a roof of a building, the roof is not constituted by incombustible materials only but instead includes also combustible materials based on the solar cell modules. Therefore, for the solar cell module, it is imperative to discuss fire safety.
There has been proposed a solar cell module having a surface covering material comprising an incombustible inorganic material such as glass or the like. This solar cell module is still insufficient in terms of incombustibility. For instance, Japanese Unexamined Patent Publication No. 148614/1997 discloses a solar cell module whose front side is protected by a tempered glass and which has a porous and incombustible absorber supported by a support at the back side. In this document, there is described that this solar cell module has advantages in that when the tempered glass as the front side protective member is broken by radiated heat or flame when a fire is occurs, the broken tempered glass is prevented from being scattered by means of the absorber and the support, and when the filler material of the solar cell module is heat-fused at that time, the fused material is absorbed by the absorber, whereby the fused material is prevented from flowing to the outside to cause firing. Hence, it is understood that the solar cell described in this document is still insufficient in terms of safety upon the occurrence of a fire.
For the solar cell module, in order to ensure the fire safety, besides making the solar cell module incombustible, there are also other subjects to be discussed as described below.
In the case where the solar cell module is used as a power generation source, it takes such a manner as will be described in the following in many cases. That is, a predetermined number of solar cell modules are electrically connected with each other by means of wiring cables to establish a solar cell array, and the solar cell array is electrically connected to an inverter.
For this solar cell array, there is an occasion such that, for instance, when a fire is occurs in the vicinity thereof, the coating of one or more of the wiring cables is broken by heat radiated from the fire to cause leakage or the coatings of the wiring cables are melted by said heat, whereby the wiring cables are mutually electrically contacted and as a result, they are shorted.
In particular, in the case where a great number of solar cell modules are installed on a large area roof of a building to establish a solar cell array on the roof and the solar cell array is electrically connected to an inverter provided at a desired position of the building, when the roof is subject to a spreading fire and the fire is extinguished in the early stages, there is such an occasion that the roof is partly damaged and some of the solar cell modules constituting the solar cell array survive without their power generation function being deteriorated but with their wiring cables being partially damaged due to heat radiated from the fire.
In this case, when sunlight is impinged in these surviving solar cell modules to generate electricity, a problem is liable to entail such that water used in the fire extinguishing promotes the leakage from or the short at the damaged portions of the wiring cables. When the leakage or short should be promoted in this way, there is a fear that a fire will reoccur or worker(s) engaged in the repair work will suffer from electric shock.
In order to deal with such problems, the inverter for the solar cell array is provided with a mechanism which functions to detect and signal an anomaly such as a leakage or a short occurred in the solar cell array and also functions to automatically earth the power input portion of the solar cell array to the inverter when the occurrence of the anomaly is signalled. Thus, for instance, when leakage occurs in the solar cell array, as the occurrence of such an anomaly is detected and signalled and the power input portion extending from the surviving solar cell modules to the inverter is earthed by the mechanism of the inverter, the worker engaged in the repair work is prevented from suffering from electric shock.
However, when the worker inadvertently touches the damaged portions of the wiring cables of the surviving solar cell modules, it takes a certain period of time until the incident is judged as a leakage and the power input portion extending from the surviving solar cell modules to the inverter is earthed by the mechanism of the inverter. In this case, since it takes a certain period of time until earthing of the power input portion extending from the survived solar cell modules is completed, there is an occasion in that the worker suffers from electric shock.
In order to prevent the occurrence of such a problem, it is considered that a high speed control mechanism capable of immediately judging ouch an incident as above-described as an anomaly and immediately earthing the power input portion extending from the surviving solar cell modules is provided at the inverter. But such a high speed control mechanism is not available. If such a high speed control mechanism should be acquired, a sunlight power generation apparatus comprising a solar cell array and an inverter provided with such a high speed control mechanism becomes costly.